I really feel for you Pruners, I so understand where you are coming from.
My situation is slightly different but has some similarities - I have 3 DDs aged 9, 4 and 18 months, a part time job and a husband away at sea with the Navy. My 4 year old has SN and is developmentally like a 2.5 year old, so lately we have been having so many tantrums over everything - getting dressed, having breakfast, putting her shoes on, getting in the car, getting out of the car, etc etc ad nauseaum all day long. (She can't talk which doesn't help.) I sometimes find myself wishing away the hours till bedtime. I love her (and all my girls) more than words can say but if someone came along and said here you go Sidge, I'm off with them and I'll bring them back in 24 hours I would weep with relief. Just a day off from the demands and drudgery would be bliss.
I know I'm a good mum, my girls are so loved and we do have fun, but like you I often find parenting such hard work.
Why don't they warn us about all this before we have kids??